U.S. patent number 7,349,092 [Application Number 11/256,611] was granted by the patent office on 2008-03-25 for system for reducing stress induced effects during determination of fluid optical constants.
This patent grant is currently assigned to J.A. Woollam Co., Inc. Invention is credited to Craig M. Herzinger, Blaine D. Johs, Galen L. Pfeiffer, Thomas E. Tiwald, John A. Woollam.
United States Patent |
7,349,092 |
Tiwald , et al. |
March 25, 2008 |
System for reducing stress induced effects during determination of
fluid optical constants
Abstract
A system for determination of optical constants of liquids,
including provision for reducing stress induced effects while
obtaining data.
Inventors: |
Tiwald; Thomas E. (Lincoln,
NE), Woollam; John A. (Lincoln, NE), Pfeiffer; Galen
L. (Lincoln, NE), Johs; Blaine D. (Lincoln, NE),
Herzinger; Craig M. (Lincoln, NE) |
Assignee: |
J.A. Woollam Co., Inc (Lincoln,
NE)
|
Family
ID: |
39199249 |
Appl.
No.: |
11/256,611 |
Filed: |
October 24, 2005 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
11098669 |
Apr 2, 2005 |
7239391 |
|
|
|
10238241 |
Sep 10, 2002 |
6937341 |
|
|
|
09756515 |
Jan 9, 2001 |
6455853 |
|
|
|
60183977 |
Feb 22, 2000 |
|
|
|
|
60318518 |
Sep 10, 2001 |
|
|
|
|
60623633 |
Nov 1, 2004 |
|
|
|
|
Current U.S.
Class: |
356/369;
356/135 |
Current CPC
Class: |
G01N
21/0303 (20130101); G01N 21/211 (20130101) |
Current International
Class: |
G01N
21/41 (20060101); G01J 4/00 (20060101) |
Field of
Search: |
;356/128,135,369 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Punnoose; Roy M
Attorney, Agent or Firm: Welch; James D.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a Continuation-In-Part of application Ser. No.
11/098,669 Filed Apr. 2, 2005 now U.S. Pat. No. 7,239,391; and
therevia of Allowed application Ser. No. 10/238,241 Filed Sep. 10,
2002, (now U.S. Pat. No. 6,937,341); and therevia of application
Ser. No. 09/756,515 Filed Jan. 9, 2001, (now U.S. Pat. No.
6,455,853) and therevia Claims benefit of Provisional Application
Ser. No. 60/183,977 Filed Feb. 22, 2000. This application further
Claims Benefit of Provisional Application Ser. No. 60/318,518,
Filed Sep. 10, 2001 via application Ser. No. 10/238,241. This
application directly Claims benefit of Provisional Application Ser.
No. 60/623,633, Filed Nov. 1, 2004.
Claims
We claim:
1. A system for use in investigating optical properties of a liquid
comprising: a prism element comprising first, second and third
substantially flat sides, the second side of which is extended
laterally beyond projected meeting points with the first and third
sides; a second element comprising closed sides and top and an open
bottom; the laterally extended second side of said prism being
placed into functional contact with said second element at the
bottom thereof to form a liquid containing cavity; such that
leakage of liquid, which liquid is caused to be present in said
liquid containing cavity, does not occur through said contact
point; such that in use liquid is caused to be present in said
liquid containing cavity and electromagnetic radiation is caused to
enter said first or third side of said prism, interact with said
second side thereof, and totally internally reflect through said
third or first side thereof, respectively.
2. A system as in claim 1, which is rotated to orient the open
bottom to face other than downward.
3. A system for use in investigating optical properties of a liquid
comprising: a prism comprising first (1st), second (2nd) and third
(3rd) substantially flat sides; an intermediate element (IE); a
third (3) element comprising closed sides and top and an open
bottom; wherein said second (2nd) side of said prism (P) is affixed
to said intermediate element (IE) by substantially stress free
means, and wherein said intermediate element (IE) when placed into
contact with the bottom of said third (3) element forms a liquid
(L) containing cavity (3c), said third (3) element and intermediate
element (IE) being forced into functional contact with one another
such that leakage of liquid (L), which liquid is caused to be
present in said liquid containing cavity (3C), does not occur
through said contact point; such that in use liquid can be caused
to be present in said liquid containing cavity (3C) and
electromagnetic radiation can be caused to enter said first (1st)
or third (3rd) side of said prism (P), interact with said second
(2nd) side thereof, totally internally reflect and exit through
said third (3rd) or first (1st) side thereof.
4. A system and in claim 3 in which said intermediate element
comprises a cavity sequestered therewithin.
5. A system as in claim 4, in which said intermediate element
cavity is filled with a fluid.
6. A system and in claim 3 in which the cavity of the intermediate
element is continuous with the liquid containing cavity of the
third element.
7. A system as in claim 3 in which the prism and intermediate
element are of single piece construction.
8. A system as in claim 3, which is rotated to orient the open
bottom to face other than downward.
9. A system for use in investigating optical properties of a liquid
comprising: a half sphere or half cylinder element comprising a
first curved and second substantially flat side, the second side of
which is extended laterally beyond the points of intersection of
first curved side; a second element comprising closed sides and top
and an open bottom; the laterally extended second side of said half
sphere or half cylinder being placed into functional contact with
said second element at the bottom thereof to form a liquid
containing cavity; such that leakage of liquid, which liquid is
caused to be present in said liquid containing cavity, does not
occur through said contact point; such that in use liquid is caused
to be present in said liquid containing cavity and electromagnetic
radiation is caused to enter said first curved side of said half
sphere or half cylinder, interact with said second side thereof,
totally internally reflect therefrom and exit through said first
curved side thereof, respectively.
10. A system and in claim 9 in which said intermediate element
comprises a cavity sequestered therewithin.
11. A system and in claim 9 in which the cavity of the intermediate
element is continuous with the liquid containing cavity of the
third element.
12. A system as in claim 9 in which the half sphere or half
cylinder and intermediate element are of single piece
construction.
13. A system as in claim 9, which is rotated to orient the open
bottom to face other than downward.
14. A system for use in investigating optical properties of a
liquid comprising: a half sphere or half cylinder comprising first
(1st) curved and second (2nd) substantially flat side; an
intermediate element (IE); a third (3) element comprising closed
sides and top and an open bottom; wherein said second (2nd)
substantially flat side of said half sphere or half cylinder (P) is
affixed to said intermediate element (IE) by substantially stress
free means, and wherein said intermediate element (IE) when placed
into contact with the bottom of said third (3) element forms a
liquid (L) containing cavity (3C), said third (3) element and
intermediate element (IE) being forced into functional contact with
one another such that leakage of liquid (L), which liquid is caused
to be present in said liquid containing cavity (3C), does not occur
through said contact point; such that in use liquid can be caused
to be present in said liquid containing cavity (3C) and
electromagnetic radiation can be caused to enter said first (1st)
curved side of said half sphere or half cylinder (P), interact with
said second (2nd) substantially flat side thereof, totally
internally reflect therefrom and exit through said first half
sphere or half cylinder first (1st) curved side thereof.
15. A system as in claim 10, in which said intermediate element
cavity is filled with a fluid.
16. A system as in claim 14, which is rotated to orient the open
bottom to face other than downward.
17. A method of determining the optical properties of a liquid
comprising the steps of: a) providing a system for use in
investigating optical properties of a liquid comprising a selection
from the group consisting of: a prism element comprising first,
second and third substantially flat sides, the second side of which
is extended laterally beyond projected meeting points with the
first and third sides; and a half sphere or half cylinder element
comprising a first curved and second substantially flat side, the
second side of which is extended laterally beyond the points of
intersection of first curved side; said system further comprising a
second element comprising closed sides and top and an open bottom;
the laterally extended second side of said prism, half sphere or
half cylinder element being placed into functional contact with
said second element at the bottom thereof to form a liquid
containing cavity, such that leakage of liquid, which liquid is
caused to be present in said liquid containing cavity, does not
occur through said contact point; such that in use liquid can be
caused to be present in said liquid containing cavity and
electromagnetic radiation can be caused to enter said first curved
side of said half sphere or half cylinder element, or enter said
first or third side of said prism, interact with said second
substantially flat side of said half sphere or half cylinder
element or said prism, totally internally reflect therefrom and
exit through said first curved side of said half sphere or half
cylinder element or said third or first side thereof, respectively;
b) causing said liquid containing cavity to contain a liquid; c)
causing electromagnetic radiation to enter said first curved side
of said half sphere or half cylinder element or enter said first or
third side of said prism, interact with said substantially flat
second side thereof, totally internally reflect and exit through
said curved side of said half sphere or half cylinder element or
said third or first side thereof respectively and enter a detector;
d) analyzing data provided by the detector in response to the
electromagnetic radiation that enters thereinto to the end that
optical properties of the liquid are determined.
18. A method as in claim 17, which comprises an additional step
comprising rotating the system to orient the open bottom to face
other than downward.
Description
TECHNICAL FIELD
The disclosed invention relates to systems for use in investigating
optical properties of materials, and more particularly to a system
for reducing stress induced effects during determination of optical
constants of liquids which is well suited for use in polarimeter,
ellipsometer and the like systems with wavelengths in VUV, UV,
Visible, Infrared, Far Infrared, and Radio ranges.
BACKGROUND
As disclosed in Co-pending Allowed application Ser. No. 10/238,241,
the characterization of fluid samples, such as biological samples,
is increasing in importance. Further, it is known to investigate a
sample placed on a first surface of a sample stage element, which
sample stage element presents with first and second, typically, but
not necessarily substantially parallel surfaces, by utilizing an
electromagnetic beam applied from said first surface side of said
sample stage element such that said beam reflects from said sample
into a detector. It is further known to independently investigate a
sample placed on a sample stage element first surface utilizing an
electromagnetic beam applied from a second, oppositely facing
surface side of said sample stage element such that said beam
reflects from the sample into a detector. Of course the sample
stage element must be transparent to said electromagnetic radiation
applied from the second surface side thereof in order to access the
sample. Further, it is to be understood that electromagnetic
radiation can be of any functional wavelength, either
monochromatic, (ie. laser source), or spectroscopic.
The primary motivation for the disclosed invention is found in a
need to do more definitive assays and analysis in areas such as:
antibody/antigen interactions; microbiology (eg. viruses, toxins
etc.); physiological (eg. hormones); drugs (therapeutic and
illegal). In addition, the present invention finds application in
fundamental science where, for instance, bonding mechanisms and
attachment rates for proteins and/or DNA to surfaces and other
biomaterials are of interest, as well as the dielectric functions
of bulk fluids.
The application of Spectroscopic Ellipsometry (SE) to biologics
provides utility because reflectance from Bio-films on opaque
substrates is difficult to detect where intensity changes are
small. In addition Surface Plasmon Resonance (SPR), while
sensitive, has a limited spectral range and can be applied only to
limited types of substrate materials and layer thicknesses.
It is noted that a suitable system for investigating biologics must
be relatively immune to such as temperature sensitive birefringence
of electromagnetic wavelength windows, which requires careful
design and mounting. And, while not related to measurement
apparatus, temperature sensitivity of reagents and reactions and
reagent concentration sensitivity can enter artifacts into results,
hence a suitable system for investigating biologics must provide
means to minimize random effects therein. A robust system and
method therefore should provide compensation capability, at least
to compensate the identified birefringence, during data in
analysis.
Another source of birefringence is pressure applied to a system to
hold elements in place with respect to one another.
Continuing, while the herein disclosed invention can be used in any
material system investigation system such as Polarimeter,
Reflectometer, Spectrophotometer and the like Systems, an important
application is with Ellipsometer Systems, whether monochromatic or
spectroscopic. It should therefore be understood that Ellipsometry
involves acquisition of sample system characterizing data at single
or multiple Wavelengths, and/or at one or more
Angle(s)-of-Incidence (AOI) of a Beam of Electromagnetic Radiation
to a surface of the sample system. Ellipsometry is generally well
described in a great many publication, one such publication being a
review paper by Collins, titled "Automatic Rotating Element
Ellipsometers: Calibration, Operation and Real-Time Applications",
Rev. Sci. Instrum., 61(8) (1990).
A typical goal in ellipsometry is to obtain, for each wavelength
in, and angle of incidence of said beam of electromagnetic
radiation caused to interact with a sample system, sample system
characterizing PSI and DELTA values, where PSI is related to a
change in a ratio of magnitudes of orthogonal components
r.sub.p/r.sub.s in said beam of electromagnetic radiation, and
wherein DELTA is related to a phase shift entered between said
orthogonal components r.sub.p and r.sub.s, caused by interaction
with said sample system. This is expressed by:
TAN(.psi.)e.sup.i(.DELTA.)=r.sub.s/r.sub.p. (Note the availability
of the phase DELTA (.DELTA.) data is a distinguishing factor
between ellipsometry and reflectometry).
Continuing, Ellipsometer Systems generally include a source of a
beam of electromagnetic radiation, a Polarizer, which serves to
impose a state of polarization on a beam of electromagnetic
radiation, a Stage for supporting a sample system, and an Analyzer
which serves to select a polarization state in a beam of
electromagnetic radiation after it has interacted with a material
system, and passed it to a Detector System for analysis therein. As
well, one or more Compensator(s) can be present and serve to affect
a phase angle between orthogonal components of a polarized beam of
electromagnetic radiation. A number of types of ellipsometer
systems exist, such as those which include rotating elements and
those which include modulation elements. Those including rotating
elements include Rotating Polarizer (RP), Rotating Analyzer (RA)
and Rotating Compensator (RC). A preferred embodiment is a Rotating
Compensator Ellipsometer System because, it is noted, Rotating
Compensator Ellipsometer Systems do not demonstrate "Dead-Spots"
where obtaining data is difficult. They can read PSI and DELTA of a
Material System over a full Range of Degrees with the only
limitation being that if PSI becomes essentially zero (0.0), DELTA
can not then be determined as there is not sufficient PSI Polar
Vector Length to form the angle between the PSI Vector and an "X"
axis. In comparison, Rotating Analyzer and Rotating Polarizer
Ellipsometers have "Dead Spots" at DELTA's near 0.0 or 180 Degrees
and Modulation Element Ellipsometers also have "Dead Spots" at PSI
near 45 Degrees). The utility of Rotating Compensator Ellipsometer
Systems should then be apparent. Another benefit provided by fixed
Polarizer (P) and Analyzer (A) positions is that polarization state
sensitivity to input and output optics during data acquisition is
essentially non-existent. This enables relatively easy use of optic
fibers, mirrors, lenses etc. for input/output.
Further, it is to be understood that causing a polarized beam of
electromagnetic radiation to interact with a sample system
generally causes change in the ratio of the intensities of
orthogonal components thereof and/or the phase angle between said
orthogonal components. The same is generally true for interaction
between any system component and a polarized beam of
electromagnetic radiation. In recognition of the need to isolate
the effects of an investigated sample system from those caused by
interaction between a beam of electromagnetic radiation and system
components other than said sample system, (to enable accurate
characterization of a sample system per se.), this Specification
incorporates by reference the regression procedure of U.S. Pat. No.
5,872,630 to Johs et al. in that it describes simultaneous
evaluation of sample characterizing parameters such as PSI and
DELTA, as well system characterizing parameters, and this
Specification also incorporates by reference the Vacuum Chamber
Window Correction methodology of U.S. Pat. No. 6,034,777 to Johs et
al. to account for phase shifts entered between orthogonal
components of a beam of electromagnetic radiation, by disclosed
invention system windows and/or beam entry elements.
A Published patent application of which the Applicants are aware is
US 2002/0024668 by Stehle et al. This application discloses the use
of two electromagnetic beams applied orthogonally to a sample, and
one electromagnetic beam applied normally thereto through effective
windows which are oriented parallel to the surface of the
sample.
Other patents of which the Inventor is aware include U.S. Pat. No.
5,757,494 to Green et al., in which is taught a method for
extending the range of Rotating Analyzer/Polarizer ellipsometer
systems to allow measurement of DELTA'S near zero (0.0) and
one-hundred-eighty (180) degrees. Said patent describes the
presence of a window-like variable birefringent components which is
added to a Rotating Analyzer/Polarizer ellipsometer system, and the
application thereof during data acquisition, to enable the
identified capability.
A patent to Thompson et al. U.S. Pat. No. 5,706,212 teaches a
mathematical regression based double Fourier series ellipsometer
calibration procedure for application, primarily, in calibrating
ellipsometers system utilized in infrared wavelength range.
Birefringent window-like compensators are described as present in
the system thereof, and discussion of correlation of retardations
entered by sequentially adjacent elements which do not rotate with
respect to one another during data acquisition is described
therein.
A patent to Woollam et al, U.S. Pat. No. 5,582,646 is disclosed as
it describes obtaining ellipsometric data through windows in a
vacuum chamber, utilizing other than a Brewster Angle of
Incidence.
Patent to Woollam et al, U.S. Pat. No. 5,373,359, patent to Johs et
al. U.S. Pat. No. 5,666,201 and patent to Green et al., U.S. Pat.
No. 5,521,706, and patent to Johs et al., U.S. Pat. No. 5,504,582
are disclosed for general information as they pertain to Rotating
Analyzer ellipsometer systems.
Patent to Bernoux et al., U.S. Pat. No. 5,329,357 is identified as
it describes the use of optical fibers as input and output means in
an ellipsometer system.
U.S. Pat. No. 5,991,048 To Karlson et al. describes a system for
practicing Surface Plasmon Resonance in which a light pipe
arrangement is present upon which can be situated a flow cell.
Sample entered to the flow cell becomes situated on the upper
surface of the light pipe and light entered to the light pipe
interacts with it from below, then exists and enters a
multi-element detector at various angles.
U.S. Pat. No. 6,316,274 B1 to Herron et al. describes a single
light source system for practicing multi-analyte homogeneous
flouro-immunoassays, via detecting of reflected and transmitted
beams.
U.S. Pat. No. 5,313,264 to Ivarsson et al. describes a single light
source system in which a light beam accesses a sample via a prism,
(which can be semicircular in shape), and reflects into a
detector.
U.S. Pat. No. 4,159,874 to Dearth et al. describes another single
light source system which includes upper and lower sensors.
U.S. Pat. No. 6,200,814 B1 to Malmquist et al. describes a method
and system for providing laminar flow over one or more discrete
sensing areas.
U.S. Pat. No. 4,076,420 to De Maeyer et al. describes a system for
investigating fast chemical reactions by optical detection of, for
instance, absorption or fluorescence or scattered light, including
detection of polarized light.
Patents identified during the preparation and prosecution of
Pending application Ser. No. 09/756,515, from which this
Application is a CIP are:
U.S. Pat. No. 5,625,455 to Nash et al.;
U.S. Pat. No. 5,486,701 to Norton et al.;
U.S. Pat. No. 5,900,633 to Solomon et al.;
U.S. Pat. No. 4,807,994 to Felch et al.;
U.S. Pat. No. 4,472,633 to Motooka;
U.S. Pat. No. 6,049,220 to Borden et al.
U.S. Pat. No. 6,738,139 to Synowicki is disclosed as it describes
determining optical constants of fluids using thin films
thereof.
Scientific Articles are also identified as follows:
"Determination of the mid-IR optical Constants of Water and
Lubricants Using IR Ellipsometry Combined with ATR an Cell" Tiwald
et al., Thin Solids Films, 313-314 (1998).
An article by Johs, titled "Regression Calibration Method For
Rotating Element Ellipsometers", which appeared in Thin Film
Solids, Vol. 234 in 1993 is also identified as it describes an
approach to ellipsometer calibration.
Another paper, by Straaher et al., titled "The Influence of Cell
Window Imperfections on the Calibration and Measured Data of Two
Types of Rotating Analyzer Ellipsometers", Surface Sci., North
Holland, 96, (1980), describes a graphical method for determining a
plane of incidence in the presence of windows with small
retardation.
An article by Collins titled "Automated Rotating Element
Ellipsometers: Calibration, Operation, and Real-Time Applications",
Rev. Sci. Instrum. 61(8), August 1990 is disclosed for the general
insight to ellipsometer systems it provides.
An article by Kleim et al. titled "Systematic Errors in
Rotating-Compensator Ellipsometry" published in J. Opt. Soc.
Am./Vol. 11, No. 9, September 1994 is identified as it describes
calibration of rotating compensator ellipsometers.
An Article by An and Collins titled "Waveform Analysis With Optical
Multichannel Detectors: Applications for Rapid-Scan Spectroscopic
Ellipsometer", Rev. Sci. Instrum., 62 (8), August 1991 is also
identified as it discusses effects such as Detection System Error
Characterization, Stray Light, Image Persistence etc., and
calibration thereof.
A paper which is co-authored by an inventor herein is titled "In
Situ Multi-Wavelength Ellipsometric Control of Thickness and
Composition of Bragg Reflector Structures", by Herzinger, Johs,
Reich, Carpenter & Van Hove, Mat. Res. Soc. Symp. Proc., Vol.
406, (1996) is also disclosed.
A paper by Nijs & Silfhout, titled "Systematic and Random
Errors in Rotating-Analyzer Ellipsometry", J. Opt. Soc. Am. A.,
Vol. 5, No. 6, (June 1988) is also identified.
An article by Jellison Jr. titled "Data Analysis for Spectroscopic
Ellipsometry", Thin Film Solids, 234, (1993) is also disclosed.
Papers of interest in the area by Azzam & Bashara; "Unified
Analysis of Ellipsometry Errors Due to Imperfect Components
Cell-Window Birefringence, and Incorrect Azimuth Angles", J. of the
Opt. Soc. Am., Vol 61, No. 5, (May 1971); "Analysis of Systematic
Errors in Rotating-Analyzer Ellipsometers", J. of the Opt. Soc.
Am., Vol. 64, No. 11, (November 1974).
An unpublished article by Poksinski et al. titled "Total Internal
Reflection Ellipsometry", describes application of total internal
reflection to investigate protein using ellipsometric
techniques.
Further identified is a flyer from Harrick, titled "Internal
Reflection/ATR".
It is also mentioned that a book by Azzam and Bashara titled
"Ellipsometry and Polarized light" North-Holland, 1977 is disclosed
and incorporated herein by reference for general theory, as is a
book which is authority regarding mathematical regression, (ie. a
book titled Numerical Recipes in "C", 1988, Cambridge University
Press.
Continuing, it is known to place a prism comprising 1st, 2nd and
3rd sides, atop of a material and direct electromagnetic radiation
along a perpendicular to the 1st side thereof so that it totally
internally reflects from the 2nd surface thereof, then exits via
the 3rd side thereof. It is also known to place such a prism atop a
liquid containing system, and apply sufficient pressure to said
prism to effect good contact between said prism's 2nd side and said
liquid, while applying electromagnetic radiation, as just
described, to investigate optical properties of said liquid. A
problem, arises, however, in that applying pressure to the prism
causes it to introduce stress induced effects into obtained
data.
It is also known to mount systems to be analyzed by electromagnetic
radiation on vertically oriented stages such that the surface of a
sample to be investigated faces laterally. When a vertical mounting
is utilized, however, to monitor liquids, some means for containing
liquid is necessary.
In view of the foregoing, a system was disclosed in application
Ser. No. 10/238,241, Filed Sep. 10, 2002, for enabling
substantially simultaneous investigation of a fluid sample with at
least two electromagnetic radiation beams comprises a sample stage
element having a first surface, and a second surface, typically,
but not necessarily substantially parallel to said first surface.
Said system further comprises a cell adjacent to said first sample
stage element surface which comprises: input and output windows;
input and output means for entering and exiting fluid sample; an
internal volume which is substantially closed but which has an
opening adjacent to said sample stage element first surface such
that fluid sample entered into said cell via said input means can
access said adjacent sample stage surface. Said system further
comprises a beam entry element in functional combination with said
sample stage element second surface.
In use fluid sample is entered to said cell through said input
means for entering fluid sample, and one electromagnetic radiation
beam is entered through said input window of said cell which is
adjacent to one surface of the sample stage element, and a second
electromagnetic radiation beam is entered through said beam entry
element adjacent to said sample stage element second surface. All
entering and exiting electromagnetic radiation preferably enters
and exits through window or beam entry element surfaces which are
oriented substantially normal to the locus thereof.
It is noted that the beam entry element through which said second
electromagnetic radiation beam is entered is preferably of a shape
selected from the group consisting of: prism; half-spherical; and
half-cylinder; and made of a material with is substantially
transparent to said second beam contained wavelengths.
In addition, the cell can be separated from said sample stage first
surface by gasket or "O" ring means or the like, such that fluid
sample entered into said cell becomes present within said gasket or
"O" ring means or the like on said sample stage first surface.
It should also be understood that at least two elements selected
from the group: sample stage element; cell; and beam entry element;
can be integrated into one another. For instance, the cell can be
continuous with the first surface of the sample stage element,
and/or the sample stage element and the beam entry element can be
of a continuous construction.
An "integrated" system for enabling substantially simultaneous
investigation of a fluid sample with at least two electromagnetic
radiation beams can then be described as comprising a cell with
effective input and output windows; input and output means for
entering and exiting fluid sample and an internal volume, said
integrated system further comprising a beam entry element in
functional combination with said cell, and located therebelow, as
the integrated system is viewed in upright side elevation. In use
fluid sample is entered to said cell through said input means for
entering fluid sample, and one electromagnetic radiation beam is
entered through said effective input window of said cell, and a
second electromagnetic radiation beam is entered through said beam
entry element. As before, all entering and exiting electromagnetic
radiation preferably enters and exits through effective cell window
or beam entry element surface(s) which are oriented substantially
normal to the locus thereof. And, again, the effective input and
output windows and the beam entry element, through which
electromagnetic radiation beams are passed can be of a shape
selected from the group consisting of: prism; half-spherical; and
half-cylinder. The input and output windows can also be of separate
construction. Further, in one variation the cell and beam entry
element are of continuous construction.
Another recitation of a presently disclosed system for enabling
substantially simultaneous investigation of a fluid sample with at
least two electromagnetic radiation beams provides that said system
comprise a cell, which cell comprises:
effective input and output windows;
input and output means for entering and exiting fluid sample;
an internal volume presenting with a surface therewithin.
Said system further comprises a beam entry element in functional
combination with said cell, and being located, as viewed in upright
side elevation, below said surface within said cell. In use fluid
sample is entered to the internal volume of said cell through said
input means for entering fluid sample, and one electromagnetic
radiation beam is entered through said effective input window of
said cell, and a second electromagnetic radiation beam is entered
through said beam entry element, to the end that both said first
and second electromagnetic beams interact, at the same or different
magnitude oblique angles with respect to said surface in said
internal volume of said cell, with said fluid sample present on
said surface, and then exit and enter detector means.
Further, in any embodiment, the cell can also comprise a third
window and a third electromagnetic beam can be caused to enter said
internal volume therethrough at a substantially normal angle of
incidence to said surface within said internal volume, transmit
through, (or reflect from), said sample caused to be present on
said surface, and enter a detector. Typically such a third beam
will not be subject to having a polarization state imposed
thereupon and is utilized to determine intensity attenuation
resulting from interaction, (transmission or reflection via beam
splitter), with said sample.
Note that the terminology "effective" input and output windows is
present to indicate that said windows can be locations on such as a
prism shaped, half-spherical shaped or half-cylinder shaped
element, although a typical cell has physically separate input and
output windows, and possibly a third window mounted
therewithin.
Also a method of investigating fluid sample with at least two beams
of electromagnetic radiation was proposed in application Ser. No.
10/238,241, that comprises the steps of:
a. providing a system as described above;
b. entering fluid sample into said cell internal volume so that it
contacts said surface therewithin;
c. causing a first beam of electromagnetic radiation to, at an
oblique angle, approach said sample directly, (not through said
stage); and
d. causing a second beam of electromagnetic radiation to approach,
at an oblique angle, said sample through said "stage" upon which it
is supported.
Reflected components of each of the at least two electromagnetic
beams are detected by one or more detector(s) and analyzed. (Single
or multiple detector systems can be utilized). Particularly, but
not exclusively, where a single detector system is used fiber
optics can be used to guide electromagnetic radiation into
different detector elements thereof.
It should also be appreciated that data is obtained from both
"sides" of a sample present on said "stage" surface inside said
cell internal volume. Use of the effective two data sets acquired
as described in a simultaneous regression allows better
determination of sample properties, such as uncorrelated thickness
and refractive index.
Another invention method disclosed in the 241 application, of
simultaneously investigating sample with at least two beams of
electromagnetic radiation, comprises the steps of:
a. providing a system for enabling substantially simultaneous
investigation of a fluid sample with at least two electromagnetic
radiation beams, said system comprising a sample stage which has
first and effective second surface sides;
such that in use one electromagnetic radiation beam is entered from
the first surface side of said sample stage, and a second
electromagnetic radiation beam is entered from the effective second
surface side of said sample stage, each at an oblique angle
thereto;
b. providing a sample on said first surface of said sample
stage;
c. causing a first beam of electromagnetic radiation to approach
said sample on said first surface from the first surface side of
said sample stage; and
d. substantially simultaneously with step c. causing a second beam
of electromagnetic radiation to approach said sample on said first
surface of the sample stage from the second effective surface side
of said sample stage.
It is noted that the terminology "substantially simultaneously" is
to be interpreted to include per se. simultaneous and at times
separated by short delays, (eg. milli-seconds to seconds or
longer).
It is also noted that the terminology "effective" second surface is
used to indicate that said "effective" second surface need not be
parallel to the first surface upon which is caused to be present
sample. In particular an "effective" second surface can be a
perimeter surface of a prism, half-spherical or half-cylinder
shaped beam entry element which is affixed to a cell, said beam
entry element forming what might be termed a base to said cell.
Further, it should be appreciated that two electromagnetic beams
can be of similar or different polarization states, wavelength
content, can be applied at the same or different
angles-of-incidence to a sample on the internal surface of the
cell, and can be substantially simultaneously applied by elements
of one, or more than one, ellipsometer system(s). For instance, a
source of electromagnetic radiation can be configured to provide
two beams, one beam being applied from the one side, and one from
the other side of a sample stage. The two beams can be, for
instance, guided via optical fibers from one or more than one
sources. And, reflected beams can be caused to enter different
detectors or the same detector, (eg. as directed by optical
fibers).
A preferred 241 application embodiment provided that an
electromagnetic beam directed toward one side of a sample stage
surface be comprised of wavelength content which differs from that
of a second beam of electromagnetic radiation directed to enter
from the other of said sample stage surface. Another preferred
embodiment provides that the two electromagnetic beams have
similar, or different, wavelength contents but are directed toward
the sample stage surface at different oblique angles-of-incidence,
(one from above and one from below the sample stage as the system
is viewed in elevation). Another preferred embodiment provides that
the two electromagnetic beams have similar, or different
polarization states imposed thereupon.
It is specifically noted that the first and/or second
electromagnetic beams mentioned above can be provided by a
selection from the group consisting of: ellipsometer; polarimeter;
which monitor changes in both the ratio of magnitudes of orthogonal
components of an electromagnetic beam and the phase angle
therebetween, as a result of interaction with a sample; or by a
selection from the group consisting of: reflectometer; and
spectrophotometer; which monitor change in intensity before and
after interaction with a sample, although the later selections are
not as relevant because birefringence of materials in intensity
measurements is not typically a critical factor.
It is emphasized that the foregoing disclosed application of
ellipsometric beams to, at oblique angles of incidence, investigate
a sample from two sides thereof. It is again noted that a third
electromagnetic beam, (eg. an unpolarized intensity beam), can be
applied substantially normal to the effective surface upon which is
present a fluid sample to enable acquiring beam attenuation
transmission data, and said data can also be used in sample
analysis.
U.S. Pat. No. 5,872,630 methodology for calibration of an
ellipsometer, and U.S. Pat. No. 6,034,777 methodology for breaking
correlation between the effects of the input and output windows and
a sample being investigated, which methodology was recited in the
Background Section, can of course be added to the preceding
recitations to provide more complete methodology.
The beam entry element can be made of ZnSe, Ge or Si, (with
specific tradename examples being KRS-5, and INTRAN), to provide
Infrared transparency, with the cell windows being transparent to
UV, Visible and Near Infrared.
A need exists for a system which contains a liquid in a cavity
while data is obtained by applying electromagnetic radiation
through a prism affixed thereto, to investigate optical properties
of said liquid, wherein the system comprises a means for affixing
said prism without inducing birefringence causing stress
therein.
DISCLOSURE OF THE INVENTION
The disclosed invention is a system and method for reducing stress
in optical elements used to receive electromagnetic radiation,
direct it to a sample, and then mediate its receipt by a detector.
For instance, the optical element might be pyramid shaped and
applied to allow monitoring liquid adjacent to a side thereof which
is caused to be in contact with the liquid. Common practice is to
secure the optical element in position by applying force to an apex
thereof which is opposite said side thereof in contact with said
liquid. The present invention system comprises an additional
element to which force can be applied instead of said apex.
An embodiment of the disclosed invention is a system for use in
investigating optical properties of a liquid comprising: a prism
element comprising first, second and third substantially flat
sides, the second side of which is extended laterally beyond
projected meeting points with the first and third sides; a second
element comprising closed sides and top and an open bottom. The
laterally extended second side of said prism is placed into
functional contact with said second element at the bottom thereof
to form a liquid containing cavity, such that leakage of liquid
which is caused to be present in said liquid containing cavity does
not occur through said contact point. In use liquid is caused to be
present in said liquid containing cavity and electromagnetic
radiation is caused to enter said first or third side of said
prism, interact with said second side thereof, and totally
internally reflect through said third or first side thereof,
respectively.
A modified present invention system for use in investigating
optical properties of a liquid comprises:
a prism comprising first, second and third sides;
an intermediate element;
a third element comprising closed sides and top and an open
bottom;
wherein said second side of said prism is affixed to said
intermediate element by substantially stress free means, and
wherein said intermediate element when placed into contact with the
bottom of said third element forms a liquid containing cavity, said
third element and intermediate element being forced into functional
contact with one another such that leakage of liquid caused to be
present in said liquid containing cavity does not occur through
said contact point. In use liquid can be caused to be present in
said liquid containing cavity and electromagnetic radiation can be
caused to enter said first or third side of said prism, interact
with said second side thereof, totally internally reflect and exit
through said third or first side thereof.
The disclosed invention is a system and method for reducing stress
in optical elements used to receive electromagnetic radiation,
direct it to a sample and then mediate its receipt by a detector.
For instance, the optical element might be pyramid shaped and
applied to allow monitoring liquid adjacent to a side thereof, with
common practice being to secure it in position by applying force to
an apex thereof which is opposite said side. The present invention
system comprises an additional element to which force can be
applied instead of said apex. Said intermediate element can
comprise a cavity sequestered within said intermediate element, and
said cavity can be filled with a fluid. Alternatively, such a
cavity in the intermediate element can be continuous with the
liquid containing cavity of the third element. Another embodiment
provides that the prism and intermediate element are of single
piece construction.
A variation of the system for use in investigating optical
properties of a liquid comprises: a half sphere or half cylinder
element comprising a first curved and second substantially flat
side, the second side of which is extended laterally beyond the
points of intersection with the first curved side; a second element
comprising closed sides and top and an open bottom; the laterally
extended second side of said half sphere or half cylinder being
placed into functional contact with said second element at the
bottom thereof to form a liquid containing cavity; such that
leakage of liquid which is caused to be present in said liquid
containing cavity does not occur through said contact point; such
that in use liquid is caused to be present in said liquid
containing cavity and electromagnetic radiation is caused to enter
said first curved side of said half sphere or half cylinder,
interact with said second side thereof, and totally internally
reflect through said first curved side of said half sphere or half
cylinder, respectively.
Another variation of the present invention system for use in
investigating optical properties of a liquid comprises:
a half sphere or half cylinder comprising first curved and second
substantially flat side;
an intermediate element;
a third element comprising closed sides and top and an open
bottom;
wherein said second substantially flat side of said half sphere is
affixed to said intermediate element by substantially stress free
means, and wherein said intermediate element when placed into
contact with the bottom of said third element forms a liquid
containing cavity, said third element and intermediate element
being forced into functional contact with one another such that
leakage of liquid caused to be present in said liquid containing
cavity does not occur through said contact point; such that in use
liquid can be caused to be present in said liquid containing cavity
and electromagnetic radiation can be caused to enter said first
side of said half sphere or half cylinder, interact with said
second substantially flat side thereof, totally internally reflect
and exit through said first half sphere or half cylinder first side
thereof.
It is noted that the foregoing description described the present
invention system as viewed in elevation with one element thereof
having an open "bottom". It is to be understood that the system can
be rotated to orient the open "bottom" so that it faces other than
downward and remain within the scope of the invention.
A present invention method of determining the optical properties of
a liquid comprising the steps of:
a) providing a system for use in investigating optical properties
of a liquid comprising a selection from the group consisting of: a
prism element comprising first, second and third substantially flat
sides, the second side of which is extended laterally beyond
projected meeting points with the first and third sides; and a half
sphere or half cylinder element comprising a first curved and
second substantially flat side, the second side of which is
extended laterally beyond the points of intersection of first
curved side; said system further comprising a second element
comprising closed sides and top and an open bottom; the laterally
extended second side of said prism, half sphere or half cylinder
element being placed into functional contact with said second
element at the bottom thereof to form a liquid containing cavity,
such that leakage of liquid which is caused to be present in said
liquid containing cavity does not occur through said contact point;
such that in use liquid can be caused to be present in said liquid
containing cavity and electromagnetic radiation can be caused to
enter said first curved side of said half sphere or half cylinder
element, or enter said first or third side of said prism, interact
with said second substantially flat side of said half sphere or
half cylinder element or said prism, totally internally reflect
therefrom and exit through said first curved side of said half
sphere or half cylinder element or said third or first side
thereof, respectively;
b) causing said liquid containing cavity to contain a liquid;
c) causing electromagnetic radiation to enter said first curved
side of said half sphere or half cylinder element or enter said
first or third side of said prism, interact with said substantially
flat second side thereof, totally internally reflect and exit
through said curved side of said half sphere or half cylinder
element or said third or first side thereof respectively and enter
a detector;
d) analyzing data provided by the detector in response to the
electromagnetic radiation that enters thereinto to the end that
optical properties of the liquid are determined.
Said method can involve application of a system involving an
intermediate element that extends laterally beyond projected
meeting points with the first and third sides, or laterally beyond
the points of intersection of first curved side, to which said
prism, half sphere or half cylinder element is affixed; or the
prism, half sphere or half cylinder element and intermediate
element can be merged into a single continuous element. An
additional step can comprise rotating the system to orient the open
"bottom" so that it faces other than downward.
The present invention will be better understood by reference to the
Detailed Description in conjunction with the Drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows Prior Art wherein a Liquid (L) containing Cavity is
forced against a Prism (P) by applying Force (F) to said Prism.
FIGS. 2-4 shows present invention systems for reducing the effects
of forces applied to keep system elements in contact with one
another, demonstrating both prism (solid lines) and half sphere or
half cylinder (dashed lines), shaped elements.
FIG. 5 demonstrates an ellipsometer system.
DETAILED DESCRIPTION
Turning now to the Drawings, FIG. 1 shows Prior Art wherein a
Liquid (L) containing Cavity is forced against a Prism (P) by
applying Force (F) to said Prism. Said Force (F) can cause stress
in the Prism and induce artifacts to data obtained by causing
electromagnetic radiation to pass through said Prism (P), interact
with the Prism (P)-Liquid (L) interface, and exit said Prism
(P).
FIG. 2 shows a present invention system for use in investigating
optical properties of a liquid comprising: a prism (P) element
comprising first (1st), second (2nd) and third (3rd) substantially
flat sides, the second (2nd) side of which is extended laterally
beyond projected meeting points with the first 1st and third (3rd)
sides; a second (2) element comprising closed sides and top and an
open bottom; the extended second (2nd) side of said prism (P) being
placed into functional contact with said second (2) element at the
bottom thereof, typically via at least one gasket or "O" ring or
the like means to provide a seal to fluid, to form a liquid (L)
containing cavity (2C); such that leakage of liquid which is caused
to be present in said liquid containing cavity does not occur
through said contact point; such that in use liquid (L) can be
caused to be present in said liquid (L) containing cavity (2C) and
electromagnetic radiation can be caused to enter said first (1st)
or third (3rd) side of said prism (P), interact with said second
(2nd) side thereof, and totally internally reflect through said
third (3rd) or first (1st) side thereof, respectively.
FIG. 3 shows a system for use in investigating optical properties
of a liquid comprising:
a prism comprising first (1st), second (2nd) and third (3rd)
substantially flat sides;
an intermediate element (IE);
a third (3) element comprising closed sides and top and an open
bottom;
wherein said second (2nd) side of said prism (P) is affixed to said
intermediate element (IE) by substantially stress free means, and
wherein said intermediate element (IE) when placed into functional
contact with the bottom of said third (3) element forms a liquid
(L) containing cavity (3C), said third (3) element and intermediate
element (IE) being forced into contact with one another such that
leakage of liquid (L) caused to be present in said liquid
containing cavity (3C) does not occur through said contact point;
such that in use liquid can be caused to be present in said liquid
containing cavity (3C) and electromagnetic radiation can be caused
to enter said first (1st) or third (3rd) side of said prism (P),
interact with said second (2nd) side thereof, totally internally
reflect and exit through said third (3rd) or first (1st) side
thereof.
As shown, said intermediate element (IE) can comprise a cavity (C)
sequestered therewithin, and said cavity (C), when present, can be
filled with a fluid, such as the liquid (L). Alternatively, such a
cavity (C) in the intermediate element (IE) can be continuous with
the liquid (L) containing cavity (C) of the third (3) element.
Further, it is noted that the interface between the prism (P) and
the intermediate element (IE) can have an index of refraction
matching liquid present therewithin.
It is noted that the FIG. 2 system results from the FIG. 3 system
if a solid, (eg. no cavity (C) present therein), intermediate
element (IE) is physically merged with the prism (P). When present,
the cavity (C) of the intermediate element (IE) can be continuous
with, via a pathway (PW), said liquid containing cavity (3C) of the
third element (3), so that the same liquid (L) is present in
both.
FIG. 4 shows an embodiment which provides that the prism (P) and
intermediate element (IE) are merged and of single piece
construction. This system results in the prism (P) and second (2)
element of FIG. 2 are physically merged.
FIG. 5 shows a general ellipsometer system. A source of
electromagnetic radiation (LS) provides a beam of electromagnetic
radiation which is caused to pass through a polarizer (POL) enter
and exit the prism (P), pass through an analyzer (ANL) and enter a
detector (DET). A compensator (COM) is also shown. In use any of
the elements (POL), (COM) or (ANL) can be caused to rotate.
Note also that FIGS. 1-4 indicate that, as indicated in dashed
lines, the prism can be replaced with a half sphere or half
cylinder. The important point being that electromagnetic radiation
can enter and exit along a locus which is perpendicular to the
surface thereof. The identifier "P" should be interpreted to
identify curved or straight intersecting sides.
Having hereby disclosed the subject matter of the present
invention, it should be obvious that many modifications,
substitutions, and variations of the present invention are possible
in view of the teachings. It is therefore to be understood that the
invention may be practiced other than as specifically described,
and should be limited in its breadth and scope only by the
Claims.
* * * * *